Steady Sea Level Rise Acceleration

A few hundred billion tons of glacial ice is melting every year due to the effects of climate change. This threatens to lead to a sea level rise that may create a future migration crisis far worse than any others in the recent era.

Global sea level rise is not cruising along at a steady 3 mm per year, it’s accelerating a little every year, like a driver merging onto a highway, according to a powerful new assessment led by CIRES Fellow Steve Nerem. He and his colleagues harnessed 25 years of satellite data to calculate that the rate is increasing by about 0.08 mm/year every year — which could mean an annual rate of sea level rise of 10 mm/year, or even more, by 2100.

“This acceleration, driven mainly by accelerated melting in Greenland and Antarctica, has the potential to double the total sea level rise by 2100 as compared to projections that assume a constant rate — to more than 60 cm instead of about 30.” said Nerem, who is also a professor of Aerospace Engineering Sciences at the University of Colorado Boulder. “And this is almost certainly a conservative estimate,” he added. “Our extrapolation assumes that sea level continues to change in the future as it has over the last 25 years. Given the large changes we are seeing in the ice sheets today, that’s not likely.”

If the oceans continue to change at this pace, sea level will rise 65cm (26 inches) by 2100 — enough to cause significant problems for coastal cities, according to the new assessment by Nerem and several colleagues from CU Boulder, the University of South Florida, NASA Goddard Space Flight Center, Old Dominion University, and the National Center for Atmospheric Research. The team, driven to understand and better predict Earth’s response to a warming world, published their work today in the journal Proceedings of the National Academy of Sciences.

Rising concentrations of greenhouse gases in Earth’s atmosphere increase the temperature of air and water, which causes sea level to rise in two ways. First, warmer water expands, and this “thermal expansion” of the oceans has contributed about half of the 7 cm of global mean sea level rise we’ve seen over the last 25 years, Nerem said. Second, melting land ice flows into the ocean, also increasing sea level across the globe.

Lamenting the Loss of Most Coral Reefs

Another consequence of climate change in this world is the disappearance of beautiful coral reefs.

coral-reefs

For decades, marine scientists have been warning of the demise of coral reefs in a warming world. But now, those warning calls have reached a full-scale alarm, leaving researchers at a loss for exactly how best to save the reefs.

A study published Thursday in Science by some of the world’s top coral experts amounts to a last rites for the ecosystems often referred to as “the tropical rainforests of the sea.” Scientists surveyed 100 reefs around the world and found that extreme bleaching events that once occurred every 25 or 30 years now happen about every five or six years.

Bleaching happens when corals become overheated and expel the symbiotic algae that feed them. Without the algae to photosynthesize their food for them, corals stop growing and become more susceptible to disease. If water temperatures remain too high for too long, the corals can die.

With the time transpiring between bleaching events shortened by a factor of five, there isn’t adequate time for the ecosystems to recover. Even the fastest-growing corals that survive a major bleaching event need about 10 years to regain their health. These damaging events are now occurring more quickly virtually eliminates any serious chance of large-scale recovery on a global scale. Huge portions of the world’s reefs face almost certain death — and that loss will reverberate beyond earth’s oceans.

“These impacts are stacking up at a pace and at a severity that I never had anticipated, even as an expert,” says Kim Cobb, a climate scientist and coral researcher at the Georgia Institute of Technology. “It’s really the rapidity of it that is so sobering and shocking — and for me personally, life-altering.”

Cobb, who is not affiliated with the new study, had first-hand experience with the latest and most severe instance of global coral bleaching: a three-year event that hit almost every major reef system in the world and eventually decimated portions of the Great Barrier Reef. In 2016, around the height of the bleaching, she made a series of dives off remote Kiritimati Island, due south of Hawaii. There, Cobb watched in horror as roughly 80 percent of one of the most pristine coral ecosystems in the world died in a matter of months.

“Before the 1980s, mass bleaching of corals was unheard of,” Terry Hughes, a coral scientist at Australia’s James Cook University and lead author of the new study, said in a statement.

Hughes personally surveyed thousands of miles of the Great Barrier Reef during the 2015 and 2016 bleaching. “It broke my heart,” he told the Guardian last year.

The new study finds that 94 percent of surveyed coral reefs have experienced a severe bleaching event since the 1980s. Only six sites surveyed were unaffected. They are scattered around the world, meaning no ocean basin on Earth has been entirely spared.

The implications of these data in a warming world, taken together with other ongoing marine stressors like overfishing and pollution, are damning.

“It is clear already that we’re going to lose most of the world’s coral reefs,” says study coauthor Mark Eakin, coordinator of the National Oceanic and Atmospheric Administration’s Coral Reef Watch program. He adds that by 2050, ocean temperatures will be warm enough to cause annual bleaching of 90 percent of the world’s reefs.

For conservation biologists like Josh Drew, whose work focuses on coral reefs near Fiji, that loss of recovery time amounts to a “death warrant for coral reefs as we know them.”

“I’m not saying we’re not going to have reefs at all, but those reefs that survive are going to be fundamentally different,” says Drew, who is not affiliated with the new study. “We are selecting for corals that are effectively weedy, for things that can grow back in two to three years, for things that are accustomed to having hot water.”

Reefs are incalculably important not only as a harbor for life — they shelter about one-quarter of all marine species in just a half-percent of the ocean’s surface area — but also for human nutrition and many nation’s economies. Hundreds of millions of people worldwide depend on reef species as a primary protein source, and tourists bring tens of billions of dollars to coastal regions and island chains each year to get a peek at the underwater ecosystems.

Researchers are struggling to think about what the loss of such an integral part of the Earth might mean in the decades ahead. And scientists, like NOAA’s Eakin, have changed their outlooks on the scale of action that’s necessary to save the world’s coral reefs.

“We need to be looking at much more radical actions to preserve those reefs that we still can preserve,” he says.

In the best case, some researchers point to extreme measures like genetically modifying super corals to withstand increased temperatures, removing carbon dioxide from the atmosphere, or even geoengineering as the only remaining options for saving corals at a large scale. Another approach involves identifying the few dozen reefs around the world most likely to survive and instituting crash-conservation methods to transform each one into a kind of seed bank for future generations after climate change has stabilized.

As you might expect, each of these ideas is highly controversial. But increasingly, coral researchers are willing to support a kind of “all-of-the-above” strategy, to avoid the worst case — losing corals entirely.

“It’s scary to think of what the oceans might look like once we degrade reefs as much as they’re likely to degrade in the next 50 years,” says Georgia Tech’s Cobb. “It will be so profoundly reshaped that it’s kind of a scientific no-man’s land.”

If there’s one consensus among the coral community, it’s that this is unequivocally the last call for saving the reefs. It’s truly an all-hands-on-deck moment.

“I don’t have the hubris — and none of us have the data — to say what strategy will work and what won’t,” Cobb says. “What is categorically unacceptable for me is to not try.”

World’s Oceans Being Significantly Harmed

This report comes as some major fishing countries have agreed to halt their commercial fishing activities in the Arctic Ocean for 16 years. It will be shameful for humanity if there is more plastic than fish in the ocean in several decades.

There’s a lot humans can learn from animals too. Radar for example was developed through studying bats. It’s therefore terrible that climate change is destroying so many ecosystems that there is a lot to gain from keeping around.

While renowned naturalist Sir David Attenborough warned the world’s oceans are “under threat now as never before in human history,” green groups on Tuesday said a United Nations resolution to end plastic pollution in the world’s oceans does not go nearly far enough to combat the problem, and stressed that more urgent action is needed to eradicate the damage before it’s too late.

Attenborough’s new BBC documentary series finale airing this weekend will highlight the crisis, drawing attention to the huge amount of plastic that’s dumped into oceans and seas every year, as well as the impact of climate change, overfishing, and noise pollution on underwater wildlife.

The final episode of Blue Planet 2 will focus entirely on the damage being done, arguing that humans’ actions are the only thing capable of reversing the effects.

“For years we thought the oceans were so vast and the inhabitants so infinitely numerous that nothing we could do could have an effect upon them. But now we know that was wrong,” said Attenborough, who narrates the show, in a preview of the episode in the Guardian. “It is now clear our actions are having a significant impact on the world’s oceans…Many people believe the oceans have reached a crisis point.”

“The future of humanity, and indeed all life on Earth, now depends on us,” added Attenborough.

[…]

In addition to the damage done by plastics, Blue Planet 2 will detail the bleaching of coral reefs, which have served as ecosystems for fish and other ocean life, brought on by the warming of oceans; the damage done to water when carbon dioxide dissolves in oceans; and the harm done by noise from shipping, tourism, and fossil fuel drilling.

“There is a whole language underwater that we are only just getting a handle on,” Steve Simpson, a coral reef researcher at the University of Exeter in England, told the Guardian, explaining that high levels of noise prevent sea animals from communicating with one another.

Another researcher featured in the program concludes that it is “beyond question” that the damage to the oceans is manmade. “The shells and the reefs really, truly are dissolving. The reefs could be gone by the end of the century,” said Professor Chris Langdon of the University of Miami.

Consumers buy about one million plastic bottles per minute, according to a Guardian report earlier this year, and Attenborough stressed that a reduction in plastic use is a step people around the world can take immediately to help combat plastic’s impact on the oceans.